Commutator assembly



June 13, 1944. w 0. 2,351,021

' I COMMUTATOR ASSEMBLY Filed June 6, 1942 WITNESSES: INVENTOR (/1/ v Winfred 0.Z7z'c/r. BY

ATTORNEY Patented June 13, 1944 COMIVIUTATOR ASSEMBLY Winfred 0. Dick, Forest Hills, Pa., assignor to Westinghouse Electric-8; Manufacturing Company,,Ea-st Pittsburgh, Pa., a corporation of Pennsylvania Application June 6, 1942, Serial No. 446,043

8 Claims. (Cl. 171-321) My invention relates to commutators for dyname-electric machines, and it has particular relation to a substantially pre-seasoned V-ring commutator-assembly of a Wholly arch-bound type, preferably one which has been fabricated in the commutator-processing method set forth in an application of H. W. Graybrook, Serial No. 444,196, filed May 23, 1942, and assigned to the Westinghouse Electric & Manufacturing Company. This type of commutator-assembly is one in which the commutator-bars, with their interposed mica or other insulating bars, are baked under a constantly maintained, arch-binding pressure, and then the V-grooves in the ends of the bars accurately machined to prescribed dimensions, after which the clamping V-rings are applied, with mica or other insulating V-rings interposed in between the clamping V-rings and the V-grooves, under such conditions that only the inner conical surface of each clamping V- ring makes pressure-transmitting engagement against the inner, arch-binding surface of the V-grooves (through the intermediary of the interposed layer of the mica V-ring), the outer surface of the clamping V-ring being spaced out of pressure-transmitting engagement with respect to the outer surface of the V-grooves, so as not to press outwardly on any spot on the finished commutator-bars.

Trouble was experienced with substantially :7-

pre-seasoned V-ring commutating-assemblies of this completely arch-bound type, when this commutator was first introduced, thetrouble taking the shape of raised spots which appeared on the in the outer cylindrical commutator-surface course of operation or use of the commutator. A dismantling of the commutator disclosed in every instance, that the raised spot was due to the presence of a piece of foreign matter in the clearance-space between the outer surfaces of the clamping V-rings and the V-grooves, which were intended to be out of pressure-transmitting engagement with respect to each other.

It should be understood that, while the commutator-assembly was substantially completely pro-seasoned prior to being put into use, there was, nevertheless, a small amount of seasoning, or shrinkage of either the copper or the mica, during at least the first months or years of the actual use of the commutator, this seasoningchange occurring during use being small, but nevertheless sufiicient to cause the foreign matter which entered the aforesaid clearance-spaces in the V-grooves to press outwardly on the commutator-assembly, thus breaking or partially breaking the arch-binding pressure, and doing it spottily, in spots where the foreign matter happened to be; and aside from any slight seasoning after being put into use, the commutator is also subject to thermal expansions and contractions which might well account for the roughem'ng due to such foreign matter.

It is the principal object of my present invention to provide means, outside of the entrance to each of the clearance-spaces between the outer surfaces of the clamping V-rings and the V-grooves, for flexibly sealing said clearancespaces against the accidental entry of foreign matter thereinto.

With the foregoing and other objects in View, my invention consists in the combination, parts, means, methods, processes, and general and specific forms of embodiment, hereinafter described and claimed, and illustrated in the accompanying drawing, wherein:

Figure 1 is a fragmentary longitudinal sectional view of the commutator-end of a dynamoelectric machine embodying my invention.

Fig. 2 is a detail-view of a slightly different form of embodiment of the front-end sealingmeans for the V-ring clearance-space, and

Fig. 3 is a similar view of a still further m0dification.

In Fig. l I have shown my invention applied to a commutator-type dynamo-electric machine in the form of an alternating-current railwaytraction motor comprising a stator-member l and a rotor member 2, the latter being mounted on a shaft 3 and carrying a substantially preseasoned V-ring commutator-assembly 4 in accordance with my present invention. The commutator-assembly is made up of a number of copper commutator-bars 5, separated by mica or other insulating bars 6, the two kinds of bars being of similar size and shape, except that the insulating bars commonly project back about of an inch behind the commutator-bars, as indicated by the numeral 6, that is, the mica bars 8 are longer than the copper bars 5. lhe bars 5 and 6 are provided with V-grooves l in the ends thereof, said V-grooves having inclined inner, arch-binding surfaces 8, usually at 30 angle, and outer surfaces 9, usually at a 3 or 6 angle.

The V-grooves i are insulatingly engaged by clamping V -rings H, usually of steel, having inner conical surfaces [2, inclined at an angle matching the inner arch-binding surfaces 8 of the V-grooves, and outer surfaces [3, inclined at an angle usually matching the outer surfaces 9 of the v-grooves. The insulating engagement is provided through the intermediary of insulating V-rings 14, preferably made of sheet-mica of sufiicient thickness to withstand the maximum voltage which is applied to the commutator-memher. The relative dimensions of the clamping V-rings and the V-grooves are such that the groove-entering portions of the insulated inner, conical surfaces 12 of the clamping V-rings tightly engage the respective inner, arch-binding surfaces 8 of the V-grooves, with the insulating V-rings l4 interposed in between, and with the insulated outer surface l3 of each clamping V- ring spaced out of pressure transmitting engagement, as indicated at I5, with respect to the outer surface 9 of the associated V-groove. The outer surface [3 of each V-ring II, with its superposed portion of the mica V-ring I4, also has a an extended portion I9 which extends out of the V-groove, beyond the end of the commutatormember.

In accordance with my present invention, I not only provide the clearance-space l5 between the outer surfaces of the insulated clamping V- rings and the V-grooves, but I also provide means for flexibly sealing the entrance to each of the clearance-spaces l5, against the accidental entry of foreign matter thereinto. This sealing-means may take any one' of several different forms,

some of which are illustrated in the accompanying drawing. I

In Fig. 1, I provide both the front and rear ends I! and l8 of the commutator-assembly with a sealing-ring 2! which is disposed at the openings of the aforesaid clearance-spaces l5. 7

This sealing-ring 2| may be'in the form of a glass rope which is of sufficient cross-sectional diameter or thickness to prevent it from becoming wedged into the clearance-space l5 which it is desired to protect. This sealing-ring 2|, in each instance, is laid up against the opening of the clearance-space l5.

At the rear end l8, the rearwardly projecting /8" portions of the mica bars 6 are first treated with an insulating cement 22, which fills the spaces between the'projecting rear ends of the mica bars, at least near the portion which is engaged by the sealing-ring 2!.

At both the front and rear ends l! and E8, before assembling the clamping V-rings H, I preferably'apply a varnish-coating to the outer surfaces 9 of the V-grooves, and the adjacent surfaces of the commutator-bar assembly, the varnish-coating extending from a point such as 23 on the end of the assembly, to a point 24 inside the V-groove 1, taking care that the varnish does not extend onto the portion of the inner, arch binding surface 8 which is pressed against by the insulating clamping V-rings II.

The sealing rings 2! are preferably held in place by's'mall fillets 25 of an insulating cement or adhesive, which may have a varnish base, for holding the sealing-ring 2| both to the end of the commutator-assembly and to the extending portion l6 of the insulating rings 14.

The conditions differ at the front and rear ends of the commutator-assembly. At the rear end, the bars 5 and 6 are provided with neckportions 3i which extend radially outwardly above the cylindrical commutator-surface 32. Extending rearwardly from these neck-portions 3| are armature-connections 33, and usually cross-connections 34, which extend back in spaced relation over the extended portion E9 of the clamping and insulating V-rings H and I4. It 75 J outer surface [3 of the clamping V--ring ll.

has been customary, after the entire dynamoelectric machine has been assembled, to further fill and seal the space at the rear of the commutator-assembly, underneath these armature-connections and cross-connections 33 and 34, with an adhering sealing material 35 which is forced thereinto by means of a force-gun, or other means (not, shown). In accordance with my invention, my rear end sealing-ring 2! makes it feasible to continue to use this rear end filler 35, as the sealing-ring keeps the filler out of the clearancespace I5. In turn, the filler 35 serves the function of holding the rearwardly extending portion 19 of the insulating V-ring I4 down against the rearward ly extending portion of the clamping V-ring ll, audit also assists in completing and augmenting the seal which is provided by the sealing-ring 2| and the cement fillets 25.

At the front end, in the form of embodiment shown in Fig. l, I prefer to tie down the extended portion l9 of the insulating V.-ring with a stringband 36, which is preferably varnished or painted over, as indicated at 31, to provide a smooth glossy surface merging up into the end-surface of the commutator-assembly, from which it is easy to wipe oil and grease, and also effectively assisting in sealing the entrance to the clearance-space l5, and keeping the varnish or cement fillets 25 from hardening until after the commutator has finished its last vestiges of season'ing, during long-continued use.

In Fig. 2, instead of using the string-band 39, I apply layers of thin insulating tape 38, which is piled up onto the extending portion l6 of the mica V-ring, and built up back against the front end of the commutator-assembly.

In Fig. 3, I show a modified form of sealingmeans in which I employ a thin flexible insulating sleeve 39, of woven glass, or mica, or other sheet-insulation, which is cemented up against the outer surface 9 of the V-groove 1, inside the V-groove, and having an extending portion 49 extending out over the extended portion 16 of the mica V-ring I4. The insulating sleeve 39 may be simply pressed against the previously described varnish-coating, before it is altogether dry, which seals 01' cements the insulating sleeve 39 to the commutator-assembly. In this form of embodiment of my invention, the outer surface 9 of the V-groove is cut out a little deeper, to compensate for the thickness of the sleeve 39, so that there will be an adequate clearance-space l5 between the insulating sleeve 39 and the portion of the insulating V-ring, I4 which overlies A small varnish or cement fillet 4|, which may be of insulating adhesive material, is applied to the junction-line between the front end of the commutator-assembly and the extending portion 49: of the insulating sleeve 39. Underneath the free end of the extending portion 40, I insert an insulating shim 42, which is preferably very slightly thicker than the clearance-space 15'. This shim is pushed under the extending portion 40 of the insulating sleeve 39, as far as it will go, and the extending portion 4|], the exposed portion of the shim 42, and any remaining portion of the extended portion l6 of the insulating V-ring M, are

then securely bound down to the extended por-.

tion of the clamping V-ring H by means of a string-band 36', thus forming a dust-tight joint:

It will be understood that, many case,the rear end of the commutator-assembly may be treated in the same manner as the front end, or it may be given a separate clearance-sealing treatment,;

not necessarily the same as that which is utilized on the front end where the sealing-conditions are usually somewhat more diflicult. I have found it effective, in every instance, to utilize the rear end sealing means in-the form shown in Fig. 1, although I am not limited to this particular detail.

The drawing is not quite to scale, because of the difficulties of illustrating the small thicknesses and clearances which are involved. I prefer to utilize a clearance-space l5 or IE of the 7 order of 30 to 40 thousandths of an inch, al-

though my experiments have extended down to clearances of 10 thousandths of an inch, which, while apparently satisfactory, is considered to be liable to give trouble because of cocking or eccentricity such as might cause more clearance to appear at one point than at a diametrically opposite point, and also possibly further trouble due to a slight possible amount of further seasoning. During alternate cycles of heating and cooling of the copper bars 4, there is likely to be a small amount of both radial and longitudinal movement of the ends of the copper bars at the entrances to the V-grooves, this movement being measured perhaps in Something like a thousandth of an inch, more or less, besides a possible gradual or progressive change in dimensions if and when the commutator further seasons in actual use. I believe that it is preferable, therefore, 0

for my cementitious sealing-means to retain a certain small modicum of flexibility, at least for a considerable length of time after the commutator has been put intouse, and preferably even throughout the entire life of the commutator.

While I have illustrated my invention in several different forms of embodiment, I wish it to be understood that my invention, in its broader aspects, is not limited to any particular mode of embodiment, and I desire that the appended claims be accorded the broadest interpretation consistent with their language.

I claim as my invention:

1. A substantially pre-seasoned l-ring commutator-assembly of commutatonhars and insu-' lating bars separating the commutator-bars, said bars having V-grooves in the ends thereof, said l-grooves having inclined inner, arch-binding surfaces; insulating \'--rings; clamping V-rings having inner. conical surfaces tightly engaging the inner, arch-binding surfaces of the V-grooves, with the insulating \i -rings interposed in between, and with the outer surface of the clamping V'rings spaced out of pressure-transmitting engagement with respect to the outer surface of i the V-grooves; and means outside of the entrance to each of the clearance-spaces between the outer surfaces of the clamping -rings and the i5 grooves for flexibly sealing said clearance-space against the accidental entry of foreign matter thereinto.

2. A substantially pro-seasoned -l-ring commutator-assembly of commutator-bars and insulating bars separating the commutator-bars, said bars having V-grooves in the ends thereof, said V-grooves having inclined inner, arch-binding surfaces; clamping V-rings; insulating V- rings of sheet-material covering the portions of the clamping V-rings that enter into said V grooves; said clamping V -rings having inner, conical surfaces tightly engaging the inner, archbinding surfaces of the V-grooves, with the insulating V-rings interposed in between, and with the insulation-covered outer surface of the clamping V-rings spaced out of pressure-transmitting engagement with respect to the outer surface of the V-grooves; and means outside of the entrance to each of the clearance spaces between the insulation-covered outer surfaces of the clamping V- rings and the V-grooves for flexibly sealing said clearance-space against the accidental entry of foreign matter thereinto.

3. A substantially pro-seasoned vering commutator-assembly of commutator-bars and insulating bars separating the commutator-bars, said bars having V-grooves in the ends thereof, said V-grooves having inclined inner, arch-binding surfaces; clamping V-rings; insulating V-rings of sheet-material covering the portions of the clamping V-rings that enter into said V-grooves; said clamping-V-rings having inner, conical surfaces tightly engaging the inner, arch-binding surfaces of the V-grooves, with the insulating V-rings interposed in between and with the groove-entering portion of the insulation-covered outer surface of the clamping V-rings-spaced out of pressure-transmitting engagement with respect to the outer surface of the V-grooves, the insulation-covered outer surface of each clamping v -ring having a groove-free external portion which does not extend into the Vgrcove; means for retaining the groove-free sheet-insulation, covering said groove-free external portion of each clamping V-ring, in dust-tight relation to its clamping V-ring; a sealing-ring too thick to enter into the clearance-space between the insulation-covered outer surface of at least one clamp-' ing V-ring and its V-groove, said sealing-ring being disposed at the entrance to said clearance'-' space; and an adhering means outside of said sealing-ring for sealing said clearance-space against the accidental entry of foreign matter thereinto.

4. A substantially pre-seasoned V-ring commutator-assembly of commutator-bars and insulating bars separating the commutator-bars, said bars having V-grooves in the ends thereof, said V-grooves having inclined inner, arch-binding surfaces; clamping v-rings having inner conical surfaces having substantially the same inclination as the inclin d inner. arch-binding surface of the corresponding V-groove; insulating spacers of sheet-material; the inner, conical surfaces of the clamping V-rings tightly engaging the respective inner, arch-binding surfaces of the V- grooves, with an insulating spacer interposed in between; an insulating sleeve of sheet-material cemented to the outer surface of at least one V- groove and having an extended portion extending out of the V-groove, the groove-entering portion of said cemented sheet being spaced out of pressure-transmitting engagement with respect to the groove-entering portion of the outer surface of the associated clamping V-ring, said clamping V-ring having a groove-free external portion which does not extend into the V-groove; and means for holding the extended portion of said cemented sheet in. dust-tight relation to said external portion of the clamping V-ring.

5. A commutator-type dynamo-electric machine characterized by having a commutatorassembly of commutator-bars and insulating bars separating the commutator-bars, said bars hav-- ing V-grooves in the ends thereof, said V-grooves having inclined inner, arch-binding surfaces; the rear ends of the commutator-bars having neckportions; armature-connections extending rear- Wardly from said neck-portions; insulating V- rings; clamping V-rings having inner, conical surfaces tightly engaging the inner, arch-binding surfaces of the V-grooves, with the insulating V-rings interposed in between, and with the outer surface of the clampingV-rings spaced out of pressure-transmitting engagement with respect to the outer surface of the V-grooves; means outside of the entrance to each of the clearance-spaces between the outer surfaces of the clamping V-rings and the V-grooves for flexibly sealing said clearance-space against the accidental entry of foreign matter thereinto; and

adhering sealing-material disposed underneath the armature-connections at the rear end of the commutator-assembly for further filling and sealing the space between the commutator-bars and the clamping V-rings at that end.

6. A commutator-type dynamo-electric machine characterized by having a commutator-assembly of commutator-bars and insulating bars separating the communtator-bars, said bars having V-grooves in the ends thereof, said V-grooves having inclined inner, arch-binding surfaces; the rear ends of the commutator-bars having neck-portions; armature-connections extending rearwardly from said neck-portions; clamping V-rings; insulating V-rings of sheet-material covering the portions of the clamping V-rings that enter into said V-grooves; said clamping V- rings having inner, conical surfaces tightly engaging the inner, arch-binding surfaces of the V-grooves, with the insulating V-rings interposed in between, and with the insulation-covered outer surface of the clamping V-rings spaced out of pressure-transmitting engagement with respect to the outer surface of the V-grooves; means outside of the entrance to each of the clearancespaces between the insulation-covered outer surfaces of the clamping V-rings and the V-grooves for flexibly sealing said clearance-space against the accidental entry of foreign matter thereinto; and adhering sealing-material disposed underneath the armature-connections at the rear end of the commutator-assembly for further filling and sealing the space between the commutatorbars and the clamping V-rings at that end.

7. A commutator-type dynamo-electric machine characterized by having a commutatorassembly of commutator-bars and insulating bars separating the commutator-bars, said bars having V-grooves in the ends thereof, said V-grooves having inclined inner, arch-binding surfaces; the rear ends of the commutator-bars having neckportions; armature-connections extending rearwardly from said neck portions; clamping V- rings; insulating V-rings of sheet-material covering the portions of the clamping V-r'mgs that enter into said V-grooves; said groove-entering portion of the insulation-covered outer surface of the clamping V-rings being spaced out of pressure-transmitting engagement with respect to the outer surface of the V-grooves, the insulation-covered outer surface of each clamping V- ring having a groove-free external portion which doesnot extend into the V-groove; means for flexibly sealing the entrance to the clearancespace between the outer surface of the rear-end clamping V-ring and its V-groove; adhering sealing-material disposed underneath the armatureconnections at the rear end of the commutatorassembly for further filling and sealing the space between the commutator-bars and the clamping V-rings at that end; and sealing-means at the front end of the commutator-assembly, comprising means for retaining the groove-free sheet insulation, covering said groove-free external portion of the front-end clamping V-ring, in dust-tight relation to its clamping V-ring, a sealing-ring too thick to enter into the clearancespace between the insulation-covered outer surface of said front-end clamping V-ring and its V-groove, said sealing-ring being disposed at the entrance to said clearance-space, and an adhering means outside of said sealing-ring for sealing said clearance-space against the accidental entry of foreign matter thereinto.

8. A commutator-type dynamo-electric machine characterized by having a commutatorassembly of commutator-bars and insulating bars separating the commutator-bars, said bars having V-grooves in the ends thereof, said V-grooves having inclined inner, arch-binding surfaces; the rear ends of the commutator-bars having neckportions; armature-connections extending rearwardly from said neck-portions; clamping V- rings having inner conical surfaces having substantially the same inclination as the inclined inner, arch-binding surface of the corresponding V-groove; insulating spacers of sheet-material,

the inner, conical surfaces .of the clamping V- rings tightly engaging the respective inner, archbinding surfaces of the V-grooves, with an' insu-' lating spacer interposed in between; means for flexibly sealing the entrance to the clearancespace between the outer surface of the rear-end clamping V-ring and its V-groove; adhering sealing-material disposed underneath'the arm'ature connections at the rear end of the commutatorassembly for further filling and sealing the space between the commutator-bars and the clamping V-rings at that end; and sealing-means at the front end of the commutator-assembly; comprising an insulating sleeve of sheet-material cemented to the outer surface of the front-end V-groove and having an extended portion extending out of the V-groove, the groove-entering portion of said cemented sheet'being spaced out of pressure-transmitting engagement with respect to the groove-entering portion of the outer surface of the associated clamping v-ring, said clamping V-ring having a groove-free external portion which does not extend into the V-groove; and means for holding the extended portion of said cemented sheet in dust-tight relation to said external portion of the clamping V-ring.

W'INFRED O. DICK. 

